From detergents to cosmetic formulations, via emulsification, the chemistry of surfactants supplies an extremely varied range of products which are nowadays indispensable to our daily life. Although the market for cationic amphiphiles is quantitatively smaller than that for anionic or non-ionic amphiphiles, representing a percentage of the worldwide production of less than 10%, it is nevertheless very extensive and covers numerous applications.
Due to their toxicity, certain surfactants such as the salts of dimethyldialkyl ammonium which are present in most textile conditioners, are restricted in use, and have even been abandoned in some European countries such as Germany and the Netherlands. Under the pressure of environmental considerations, the manufacturers of surfactants are having to propose not only methods compatible with these new requirements, but also less polluting products which are more biodegradable and cause the lowest possible pollution of the environment. Added to the environmental constraints is a considerable commercial argument, of using what is “natural”. To respond to the demands of the consumer, and at pains to find products having a “green image”, the manufacturers are currently researching new structures and are naturally turning to the use of raw materials of agricultural origin.
If, for the lipophilic part of these molecules, competition is well established between the petrochemical substances and the oleochemical substances, it is not yet really engaged as far as the hydrophilic part of these molecules is concerned. The direct use of natural triglycerides, such as triglycerol ricinoleate [U.S. Pat. No. 4,857,310 (The Gillette Company)], makes it possible to have easy access to cationic amphiphilic compounds. But the diversification of the structures is effected also by modification of the polar head. Cationic surfactants, derived in particular from glucuronic acid and galacturonic acid [DE 195 39 845 (Henkel KgaA)] or with a starch base comprising a sugar entity derived from alkyl polyglycosides (APG) [WO 90 15809 (Henkel KgaA)] have been proposed. Another type of surfactant is appearing. This involves molecules having a saponifiable ester function between the fatty chain and the quaternary ammonium function, such as ammonium chlorides [U.S. Pat. No. 5,527,477 (Lever Brothers Company)]. Being easily hydrolysable, the betaine esters are also currently stirring up strong interest. Various derivatives have been synthesised ([WO 96 09276 (The Procter and Gamble Company:], [U.S. Pat. No. 5,527,477 (Lever Brothers Company)], intended for applications such as textile conditioners.
Betaine glycine, a cheap natural substance, forms a raw material of choice for the production of surfactant agents. Representing 27% by weight of sugar-beet molasses, obtained after extraction of the sucrose, it remains currently a by-product of the sugar industry. The grafting on to the betaine glycine of fatty alcohols and fatty acids ([U.S. Pat. No. 2,888,383 (International Minerals and Chemical Corporation)], [EP 0 750 904 A1 (Wella-AG)] makes it possible to obtain amphiphilic cationic molecules without the conventional stage of quaternisation of a tertiary amine using methylation agents which are generally toxic.